US6491108B1 - Drillable bridge plug - Google Patents

Abstract

A method and apparatus for use in a subterranean well. The apparatus typically includes a subterranean plug including a mandrel having an outer surface and a non-circular cross-section and a packing element arranged about the mandrel, the packing element having a non-cylindrical inner surface matching the mandrel outer surface such that concentric rotation between the mandrel and the packing element is precluded. The apparatus is substantially non-metallic to facilitate quick drill-out of the plug. The apparatus is alternatively adaptable as a cement retainer.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to methods and apparatus for drilling and completing subterranean wells and, more particularly, to methods and apparatus for a drillable bridge plug and other related downhole apparatus.

2. Description of Related Art

There are many applications in well drilling, servicing, and completion in which it becomes necessary to isolate particular zones within the well. In some applications, such as cased-hole situations, conventional bridge plugs such as the Baker Hughes model T, N1, NC1, P1, or S wireline-set bridge plugs are inserted into the well to isolate zones. The bridge plugs may be temporary or permanent, the purpose of the plugs is simply to isolate some portion of the well from another portion of the well. In some instances perforations in the well in one portion need to be isolated from perforations in another portion of the well. In other situations there may be a need to use a bridge plug to isolate the bottom of the well from the wellhead. There are also situations where these plugs are not used necessarily for isolation but instead are used to create a cement plug in the wellbore which may be used for permanent abandonment. In other applications a bridge plug with cement on top of it may be used as a kickoff plug for side-tracking the well.

Bridge plugs may be drillable or retrievable. Drillable bridge plugs are typically constructed of a brittle metal such as cast iron that can be drilled out. One typical problem with conventional drillable bridge plugs is that without some sort of locking mechanism, the bridge plug components tend to rotate with the drill bit, which may result in extremely long drill-out times, excessive casing wear, or both. Long drill-out times are highly undesirable as rig time is typically charged for by the hour.

Another typical problem with conventional drillable plugs is that the conventional metallic construction materials, even though brittle, are not easy to drill through. The plugs are generally required to be quite robust to achieve an isolating seal, but the materials of construction may then be difficult to drill out in a reasonable time. These typical metallic plugs thus require that significant weight be applied to the drill-bit in order to drill the plug out. It would be desirable to create a plug that did not require significant forces to be applied to the drill-bit such that the drilling operation could be accomplished with a coiled tubing motor and bit, however, conventional metallic plugs do not enable this.

In addition, when several plugs are used in succession to isolate a plurality of zones within the wellbore, there may be significant pressures on the plug from either side. It would be desirable to design an easily drilled bridge plug that is capable of holding high differential pressures on both sides of the plug. Also, with the potential for use of multiple plugs in the same wellbore, it would be desirable to create a rotational lock between plugs. A rotational lock between plugs would facilitate less time consuming drill outs.

The present invention is directed to overcoming, or at least reducing the effects of, one or more of the issues set forth above.

SUMMARY OF THE INVENTION

In one embodiment a subterranean apparatus is disclosed. The apparatus may include a mandrel having an outer surface and a non-circular cross-section and a packing element arranged about the mandrel, the packing element having a non-cylindrical inner surface such that rotation between the mandrel and the packing element is precluded. The mandrel may include non-metallic materials, for example carbon fiber.

In one embodiment, the apparatus exhibits a non-circular cross-section that is hexagonally shaped. The interference between the non-circular outer surface of the mandrel and the inner surface of the packing element comprise a rotational lock.

In one embodiment the apparatus includes an anchoring assembly arranged about the mandrel, the anchoring assembly having a non-circular inner surface such that rotation between the mandrel and the anchoring assembly is precluded. The anchoring assembly may farther include a first plurality of slips arranged about the non-circular mandrel outer surface, the slips being configured in a non-circular loop such that rotation between the mandrel and the slips is precluded by interference between the loop shape and the mandrel outer surface shape. The first plurality of slips may include non-metallic materials. The first plurality of slips may each include a metallic insert mechanically attached to and/or integrally formed into each of the plurality of slips wherein the metallic insert is engagable with a wellbore wall. The anchoring assembly may also include a first cone arranged about the mandrel, the first cone having a non-circular inner surface such that rotation between the mandrel and the first cone is precluded by interference between the first cone inner surface shape and the mandrel outer surface shape. The first plurality of slips abuts the first cone, facilitating radial outward movement of the slips into engagement with a wellbore wall upon traversal of the plurality of slips along the first cone. In this embodiment, the first cone may include non-metallic materials. At least one shearing device may be disposed between the first cone and the mandrel, the sharing device being adapted to shear upon the application of a predetermined force.

The anchoring assembly of the apparatus may further include a second plurality of slips arranged about the non-circular outer surface of the mandrel, the second plurality of slips, the slips being configured in a non-circular loop such that rotation between the mandrel and the slips is precluded by interference between the loop shape and the mandrel outer surface shape. The second plurality of slips may include non-metallic materials. The second plurality of slips may each include a metallic insert mechanically attached to and/or integrally formed therein with the metallic inserts being engagable with the wellbore wall. The anchoring assembly may also include a second collapsable cone arranged about the non-circular outer surface of the mandrel, the second collapsable cone having a non-circular inner surface such that rotation between the mandrel and the second cone is precluded by interference between the second cone inner surface shape and the mandrel outer surface shape, wherein the second plurality of slips abuts the second collapsable cone, facilitating radial outward movement of the slips into engagement with the wellbore wall upon traversal of the plurality of slips along the second collapsable cone. The second collapsable cone may include non-metallic materials. The second collapsable cone may be adapted to collapse upon the application of a predetermined force. The second collapsable cone may include at least one metallic insert mechanically attached to and/or integrally formed therein, the at least one metallic insert facilitating a locking engagement between the cone and the mandrel. The anchoring assembly may include at least one shearing device disposed between the second collapsable cone and the mandrel, the at least one shearing device being adapted to shear upon the application of a predetermined force.

In one embodiment the packing element is disposed between the first cone and the second collapsable cone.

In one embodiment a first cap is attached to a first end of the mandrel. The first cap may include non-metallic materials. The first cap may be attached to the mandrel by a plurality of non-metallic pins.

In one embodiment the first cap may abut a first plurality of slips.

In one embodiment the packing element includes a first end element, a second end element, and a elastomer disposed therebetween. The elastomer may be adapted to form a seal about the non-circular outer surface of the mandrel by expanding radially to seal with the wall of the wellbore upon compressive pressure applied by the first and second end elements.

In one embodiment the apparatus may include a second cap attached to a second end of the mandrel. The second cap may include non-metallic materials. The second cap may be attached to the mandrel by a plurality of non-metallic pins. In this embodiment, the second cap may abut a second plurality of slips.

In one embodiment the first end cap is adapted to rotationally lock with a second mandrel of a second identical apparatus such as a bridge plug.

In one embodiment the apparatus includes a hole in the mandrel extending at least partially therethrough. In another embodiment the hole extends all the way through the mandrel. In the embodiment with the hole extending all the way therethrough, the mandrel may include a valve arranged in the hole facilitating the flow of cement or other fluids, gases, or slurries through the mandrel, thereby enabling the invention to become a cement retainer.

In one embodiment there is disclosed a subterranean apparatus including a mandrel having an outer surface and a non-circular cross-section, and an anchoring assembly arranged about the mandrel, the anchoring assembly having a non-circular inner surface such that rotation between the mandrel and the anchoring assembly is precluded as the outer surface of the mandrel and inner surface of the packing element interfere with one another in rotation.

In one embodiment there is disclosed a subterranean apparatus including a mandrel; a first cone arranged about an outer diameter of the mandrel; a first plurality of slips arranged about first cone; a second cone spaced from the first cone and arranged about the outer diameter of the mandrel; a second plurality of slips arranged about the first cone; a metallic insert disposed in an inner surface of the second cone and adjacent to the mandrel; a packing element disposed between the first and second cones; with the first and second pluralities of slips being lockingly engagable with the wall of a wellbore and the metallic insert being lockingly engagable with the mandrel. In this embodiment the second cone may be collapsable onto the mandrel upon the application of a predetermined force. The mandrel, cones, and slips may include non-metallic materials. In addition, a cross-section of the mandrel is non-circular and the inner surfaces of the cones, slips, and packing element are non-circular and may or may not match the outer surface of the mandrel.

In one embodiment there is disclosed a slip assembly for use on subterranean apparatus including: a first cone with at least one channel therein; a first plurality of slips, each having an attached metallic insert, the first slips being arranged about the first cone in the at least one channel of the first cone; a second collapsable cone having an interior surface and an attached metallic insert disposed in the interior surface; a second plurality of non-metallic slips, each having an attached metallic insert, the second slips being arranged about the second cone; with the second non-metallic collapsable cone being adapted to collapse upon the application of a predetermined force. In this embodiment the first and second pluralities of slips are adapted to traverse first and second cones until the slips lockingly engage with a wellbore wall. The insert of the second non-metallic cone is adapted to lockingly engage with a mandrel upon the collapse of the cone. Each of first and second cones and first and second pluralities of slips may include non-metallic materials.

There is also disclosed a method of plugging or setting a packer in a well. The method may include the steps of: running an apparatus into a well, the apparatus comprising a mandrel with a non-cylindrical outer surface and a packing element arranged about the mandrel; setting the packing element by the application force delivered from conventional setting tools and means including, but not limited to: wireline pressure setting tools, mechanical setting tools, and hydraulic setting tools; locking the apparatus in place within the well; and locking an anchoring assembly to the mandrel. According to this method the apparatus may include a first cone arranged about the outer surface of the mandrel; a first plurality of slips arranged about the first cone; a second cone spaced from the first cone and arranged about the outer diameter of the mandrel; a second plurality of slips arranged about the second cone; a metallic insert disposed in an inner surface of the second cone and adjacent to the mandrel; with the first and second pluralities of slips being lockingly engagable with the wall of a wellbore and the metallic insert being lockingly engagable with the mandrel. The first and second cones may include a plurality of channels receptive of the first and second pluralities of slips. Also according to this method, the step of running the apparatus into the well may include running the apparatus such as a plug on wireline. The step of running the apparatus into the well may also include running the apparatus on a mechanical or hydraulic setting tool. The step of locking the apparatus within the well may further include the first and second pluralities of slips traversing the first and second cones and engaging with a wall of the well. The step of locking the anchoring assembly to the mandrel may further include collapsing the second cone and engaging the second cone metallic insert with the mandrel.

There is also disclosed a method of drilling out a subterranean apparatus such as a plug including the steps of: running a drill into a wellbore; and drilling the apparatus; where the apparatus is substantially non-metallic and includes a mandrel having a non-cylindrical outer surface; and a packing element arranged about the mandrel, the packing element having a non-cylindrical inner surface matching the mandrel outer surface. According to this method, the step of running the drill into the wellbore may be accomplished by using coiled tubing. Also, drilling may be accomplished by a coiled tubing motor and bit.

In one embodiment there is disclosed an adapter kit for a running a subterranean apparatus including: a bushing adapted to connect to a running tool; a setting sleeve attached to the bushing, the setting sleeve extending to the subterranean apparatus; a setting mandrel interior to the setting sleeve; a support sleeve attached to the setting mandrel and disposed between the setting mandrel and the setting sleeve; and a collet having first and second ends, the first end of the collet being attached to the setting mandrel and the second end of the collet being releasably attached to the subterranean apparatus. According to this adapter kit the subterranean apparatus may include an apparatus having a packing element and an anchoring assembly. The subterranean apparatus may include a plug, cement retainer, or packer. The anchoring assembly may be set by the transmission of force from the setting sleeve to the anchoring assembly. In addition, the packing element may be set by the transmission of force from the setting sleeve, through the anchoring assembly, and to the packing element. According to this embodiment the collet is locked into engagement with the subterranean apparatus by the support sleeve in a first position. The support sleeve first position may be facilitated by a shearing device such as shear pins or shear rings. The support sleeve may be movable into a second position upon the application of a predetermined force to shear the shear pin. According to this embodiment, the collet may be unlocked from engagement with the subterranean apparatus by moving the support sleeve to the second position.

In one embodiment there is disclosed a bridge plug for use in a subterranean well including: a mandrel having first and second ends; a packing element; an anchoring assembly; a first end cap attached to the first end of the mandrel; a second end cap attached to the second end of the mandrel; where the first end cap is adapted to rotationally lock with the second end of the mandrel of another bridge plug. According to this embodiment, each of mandrel, packing element, anchoring assembly, and end caps may be constructed of substantially non-metallic materials.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features and aspects of the invention will become further apparent upon reading the following detailed description and upon reference to the drawings in which:

FIG. 1 is a simplified view of a subterranean apparatus and adapter kit assembly positioned in a wellbore according to one embodiment of the present invention.

FIG. 2 is a top cross-sectional view of the subterranean apparatus through the upper slip and cone, according to FIG.1.

FIG. 3 is a top view of a slip ring according to one embodiment of the disclosed method and apparatus.

FIG. 4 is a side view of a cone assembly according to one embodiment of the disclosed method and apparatus.

FIG. 5 is a simplified view of the subterranean apparatus and adapter kit according to FIG. 1, shown in a second position.

FIG. 6 is a simplified view of the subterranean apparatus and adapter kit according to FIG. 1, shown in a third position.

FIG. 7 is a simplified view of the subterranean apparatus and adapter kit according to FIG. 1, shown in a fourth position.

FIG. 8 is a simplified view of the subterranean apparatus and adapter kit according to FIG. 1, shown in a fifth position.

FIG. 9 is a simplified view of the subterranean apparatus and adapter kit according to FIG1, shown in a sixth position.

FIG. 10 is a simplified view of the subterranean apparatus and adapter kit according to FIG. 1, shown in a seventh position.

FIG. 11 is a simplified view of a subterranean apparatus and adapter kit assembly positioned in a wellbore according to one embodiment of the present invention.

FIG. 12 is a simplified view of the subterranean apparatus assembly and adapter kit according to FIG11, shown in a second position.

FIG. 13 is a simplified view of the subterranean apparatus assembly and adapter kit according to FIG. 11, shown in a third position.

FIG. 13A is a cross-sectional view of the subterranean apparatus assembly according to FIG. 13 taken along line A—A.

FIG. 14 is a top cross-sectional view of the subterranean apparatus through the mandrel and packing element, an alternative embodiment of the present invention.

FIG. 15 is a top cross-sectional view of the subterranean apparatus through the mandrel and packing element, according to an alternative embodiment of the present invention.

FIG. 16 is a top cross-sectional view of the subterranean apparatus through the mandrel and packing element, according to another alternative embodiment of the present invention.

FIG. 17 is a top cross-sectional view of the subterranean apparatus through the mandrel and packing element, according to another alternative embodiment of the present invention.

FIG. 18 is a sectional view of the subterranean apparatus according to another alternative embodiment of the present invention.

FIG. 19 is a sectional view of the subterranean apparatus according to another alternative embodiment of the present invention.

FIG. 20 is a sectional view of the subterranean apparatus according to another alternative embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, that will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

Turning now to the drawings, and in particular to FIGS. 1 and 13, a subterranean plug assembly2 in accordance with one embodiment of the disclosed method and apparatus is shown. Plug assembly2 is shown in the running position in FIGS. 1 and 13. Plug assembly2 is shown as a bridge plug, but it may be modified as described below to become a cement retainer or other plug. Plug assembly2 includes amandrel4 constructed of non-metallic materials. The non-metallic materials may be a composite, for example a carbon fiber reinforced material or other material that has high strength yet is easily drillable. Carbon fiber materials for construction ofmandrel4 may be obtained from ADC Corporation and others, for example XC-2 carbon fiber available from EGC Corporation.Mandrel4 has a non-circular cross-section as shown in FIG.2. The cross-section of the embodiment shown in FIGS. 1-13 is hexagonal, however, it will be understood by one of skill in the art with the benefit of this disclosure that any non-circular shape may be used. Other non-circular shapes include, but are not limited to, an ellipse, a triangle, a spline, a square, or an octagon. Any polygonal, elliptical, spline, or other non-circular shape is contemplated by the present invention. FIGS. 14-17 disclose some of the exemplary shapes of the cross-section ofmandrel4 and the outer components. FIG. 14 discloses ahexagonal mandrel4, FIG. 15 discloses anelliptical mandrel4, FIG. 16 discloses asplined mandrel4, and FIG. 17 discloses a semi-circle and flat mandrel. In thepreferred embodiment mandrel4 may include ahole6 partially therethrough.Hole6 facilitates the equalization of well pressures across the plug at the earliest possible time if and when plug assembly2 is drilled out. One of skill in the art with the benefit of this disclosure will recognize that it is desirable in drilling operations to equalize the pressure across the plug as early in the drilling process as possible.

Mandrel4 is the general support for each of the other components of plug assembly2. The non-circular cross-section exhibited bymandrel4 advantageously facilitates a rotational lock between the mandrel and all of the other components (discussed below), i.e, if and when it becomes necessary to drill out plug assembly2,mandrel4 is precluded from rotating with the drill, the non-circular cross-section ofmandrel4 prevents rotation of the mandrel with respect to the other components which have surfaces interfering with the cross-section of the mandrel.

Attached to afirst end8 ofmandrel4 is afirst end cap10.First end cap10 is a non-metallic composite that is easily drillable, for example an injection molded phenolic or other similar material.First end cap10 may be attached tomandrel4 by a plurality of non-metallic composite pins12, and/or attached via an adhesive. Composite pins12 are arranged in different planes to distribute any shear forces transmitted thereto.First end cap10 prevents any of the other plug components (discussed below) from sliding offfirst end8 ofmandrel4.First end cap10 may include a locking mechanism, for example taperedsurface14, that rotationally locks plug assembly2 with another abutting plug assembly (not shown) without the need for a third component such as a key. This rotational lock facilitates the drilling out of more than one plug assembly when a series of plugs has been set in a wellbore. For example, if two plug assemblies2 are disposed in a wellbore at some distance apart, as the proximal plug is drilled out, any remaining portion of the plug will fall onto the distal plug, andfirst end cap10 will rotationally lock with the second plug to facilitate drilling out the remainder of the first plug before reaching the second plug. In the embodiment shown in the Figures,first end cap10 exhibits an internal surface matching the non-circular cross-section ofmandrel4 which creates a rotational lock between the end cap and mandrel, however, the internal surface of thefirst end cap10 may be any non-circular surface that precludes rotation between the end cap andmandrel4. For example, the internal surface offirst end cap10 may be square, whilemandrel4 has an outer surface that is hexagonal or octagonal, but rotation between the two is still advantageously precluded without the need for a third component such as a key.

First end cap10 abuts an anchoringassembly16. Anchoringassembly16 includes a first plurality ofslips18 arranged about the outer diameter ofmandrel4.Slips18 are arranged in a ring shown in FIG. 3 with the slips being attached to one another byslip ring20. In the embodiment shown in FIG. 3, there are sixslips18 arranged in a hexagonal configuration to match the cross-section ofmandrel4. It will be understood by one of skill in the art with the benefit of this disclosure that slips18 may be arranged in any configuration matching the cross-section ofmandrel4, which advantageously creates a rotational lock such that slips18 are precluded from rotating with respect tomandrel4. In addition, the number of slips may be varied and the shape of slip ring may be such that rotation would be allowed between the slips and the mandrel—but for the channels99 (discussed below). Further, the configuration ofslip ring20 may be any non-circular shape that precludes rotation betweenslips18 andmandrel4. For example, theslip ring20 may be square, whilemandrel4 has an outer surface that is hexagonal or octagonal, but rotation between the two is still precluded. Each ofslips18 is constructed of non-metallic composite materials such as injection molded phenolic, but each slip also includes ametallic insert22 disposed inouter surface23.Metallic inserts22 may each have a wicker design as shown in the figures to facilitate a locked engagement with acasing wall24.Metallic inserts22 may be molded intoslips18 such that slips18 and inserts22 comprise a single piece as shown in FIG. 1, however, as shown in the embodiment shown in FIGS. 11-13,metallic inserts22 may also be mechanically attached toslips18 by a fastener, for example screws23.Metallic inserts22 are constructed of low density metallic materials such as cast iron, which may heat treated to facilitate surface hardening such that inserts22 can penetratecasing24, while maintaining small, brittle portions such that they do not hinder drilling operations.Metallic inserts22 may be integrally formed withslips18, for example, by injection molding the composite material that comprises slips18 aroundmetallic insert22.

Anchoringassembly16 also includes afirst cone26 arranged adjacent to the first plurality ofslips18. A portion ofslips18 rest onfist cone26 as shown in the running position shown in FIGS. 1 and 13.First cone26 comprises non-metallic composite materials such as phenolics that are easily drillable.First cone26 includes a plurality ofmetallic inserts28 disposed in aninner surface30adjacent mandrel4. In the running position shown in FIGS. 1 and 13, there is agap32 betweenmetallic inserts28 andmandrel4.Metallic inserts28 may each have a wicker design as shown in the figures to facilitate a locked engagement withmandrel4 upon collapse offirst cone26.Metallic inserts28 may be molded intofirst cone26 such thatfirst cone26 andmetallic inserts28 comprise a single piece as shown in FIG. 1, however, as shown in the embodiment shown in FIGS. 11-13,metallic inserts28 may also be mechanically attached tofirst cone26 by a fastener, for example screws27.Metallic inserts28 may be constructed of low density metallic materials such as cast iron, which may be heat treated to facilitate surface hardening sufficient to penetratemandrel4, while maintaining small, brittle portions such that the inserts do not hinder drilling operations. For example,metallic inserts28 may be surface or through hardened to approximately plus or minus fifty-five Rockwell C hardness.Metallic inserts28 may be integrally formed withfirst cone26, for example, by injection molding the composite material that comprisesfirst cone26 aroundmetallic inserts28 as shown in FIG. 1, however, as shown in the embodiment shown in FIGS. 11-13,metallic inserts28 may also be mechanically attached tofirst cone26 by a fastener, for example screws27.Inner surface30 offirst cone26 may match the cross-section ofmandrel4 such that there is an advantageous rotational lock therebetween. In the embodiment shown in FIGS. 2 and 4,inner surface30 is shaped hexagonally to match the cross-section ofmandrel4. However, it will be understood by one of skill in the art with the benefit of this disclosure thatinner surface30 ofcone26 may be arranged in any configuration matching the cross-section ofmandrel4. The matching ofinner surface30 andmandrel4 cross-section creates a rotational lock such thatmandrel4 is precluded from rotating with respect tofirst cone26. In addition, however, theinner surface30 of thefirst cone26 may not match and instead may be any non-circular surface that precludes rotation between the first cone andmandrel4. For example, theinner surface30 may be square, whilemandrel4 has an outer surface that is hexagonal or octagonal, but rotation between the two is still advantageously precluded without the need for a third component such as a key.

As shown in FIG. 4,first cone26 includes a plurality ofslots32 disposed therein, for example six slots.Slots32 weakenfirst cone26 such that the cone will collapse at a predetermined force. The predetermined collapsing force onfirst cone26 may be, for example, approximately 4500 pounds, however,first cone26 may be designed to collapse at any other desirable force. Whenfirst cone26 collapses, as shown in FIGS. 7 and 12,metallic inserts28 penetratemandrel4 and preclude movement between anchoringassembly16 andmandrel4. As shown in FIGS. 1 and 13, one or more shearing devices, for example shear pins38, may extend betweenfirst cone26 andmandrel4. Shear pins38 preclude the premature setting of anchoringassembly16 in the wellbore during run-in. Shear pins38 may be designed to shear at a predetermined force, for example, shear pins38 may shear at a force of approximately 1500 pounds, however shear pins38 may be designed to shear at any other desirable force. As shear pins38 shear, further increases in force onfirst cone26 will cause relative movement betweenfirst cone26 and first slips,18. FIG. 6 shows the shearing of shear pins38. The relative movement betweenfirst cone26 andfirst slips18 causes first slips18 to move in a radially outward direction and into engagement withcasing wall24. At some point of the travel ofslips18 alongfirst cone26,slip ring20 will break to allow each ofslips18 to engagecasing wall24. For example,slip ring20 may break between 1500 and 3000 pounds, withslips18 being fully engaged withcasing wall24 at 3000 pounds. FIGS. 6 and 12 show plug assembly2 withslips18 penetratingcasing wall24. FIG. 4 also discloses a plurality ofchannels99 formed infirst cone26. Each ofchannels99 is associated with itsrespective slip18.Channels99 advantageously create a rotational lock betweenslips18 andfirst cone26.

First cone26 abuts agage ring40.Gage ring40 may be non-metallic, comprised, for example, of injection molded phenolic.Gage ring40 prevents the extrusion of apacking element42 adjacent thereto.Gage ring40 includes a non-circular inner surface41 that precludes rotation between the gage ring andmandrel4. For example inner surface41 may be hexagonal, matching a hexagonal outer surface ofmandrel4, but inner surface41 is not limited to a match as long as the shape precludes rotation between the gage ring and the mandrel.

Packing element42 may include three independent pieces.Packing element42 may include first andsecond end elements44 and46 with anelastomeric portion48 disposed therebetween. First andsecond end elements44 and46 may include a wire mesh encapsulated in rubber or other elastomeric material.Packing element42 includes a non-cylindricalinner surface50 that may match the cross-section ofmandrel4, for example, as shown in the Figures,inner surface50 is hexagonal. The match betweennon-cylindrical surface50 of packingelement42 and the cross-section ofmandrel4 advantageously precludes rotation between the packing element and the mandrel as shown in any of FIGS. 14-17. However, thenon-cylindrical surface50 of packingelement42 may be any non-circular surface that precludes rotation between the packing element andmandrel4. For example, thesurface50 may be hexagonal, whilemandrel4 has an outer surface that is octagonal, but rotation between the two is still precluded.Packing element42 is predisposed to a radially outward position as force is transmitted to theend elements44 and46, urging packingelement42 into a sealing engagement withcasing wall24 and the outer surface ofmandrel4.Packing element42 may seal againstcasing wall24 at, for example, 5000 pounds.

End element46 of packingelement42 abuts a non-metallicsecond cone52.Second cone52 includes non-metallic composite materials that are easily drillable such as phenolics.Second cone52 is a part of anchoringassembly16.Second cone52, similar tofirst cone26, may include a non-cylindricalinner surface54 matching the cross-section ofmandrel4. In the embodiment shown in the figures,inner surface54 is hexagonally shaped. The match betweeninner surface54 precludes rotation betweenmandrel4 andsecond cone52. However,inner surface54 may be any non-circular surface that precludes rotation betweensecond cone52 andmandrel4. For example,inner surface54 may be square, whilemandrel4 has an outer surface that is hexagonal or octagonal, but rotation between the two is still precluded. In a preferred embodiment,second cone52 does not include any longitudinal slots or metallic inserts asfirst cone26 does, however, in an alternative embodimentsecond cone52 does include the same elements asfirst cone26.Second cone52 includes one or more shearing devices, for example shear pins56, that prevent the premature setting of a second plurality ofslips58. Shear pins56 may shear at, for example approximately 1500 pounds. FIG. 4 also discloses thatsecond cone52 includes a plurality ofchannels99 formed therein, each ofchannels99 is associated with itsrespective slip58.Channels99 advantageously create a rotational lock betweenslips58 andsecond cone52.

Anchoringassembly16 further includes the second plurality ofslips58 arranged about the outer diameter ofmandrel4.Slips58 are arranged in a ring shown in FIG. 3 with the slips being attached to one another byslip ring60. In the embodiment shown in FIG. 3, there are sixslips58 arranged in a hexagonal configuration to match the cross-section ofmandrel4. It will be understood by one of skill in the art with the benefit of this disclosure that slips58 may be arranged in any configuration matching the cross-section ofmandrel4, which advantageously creates a rotational lock such that slips58 are precluded from rotating with respect tomandrel4. Further, the configuration ofslip ring60 may be any non-circular shape that precludes rotation betweenslips58 andmandrel4. For example, theslip ring60 may be square, whilemandrel4 has an outer surface that is hexagonal or octagonal, but rotation between the two is still precluded. In addition, the number of slips may be varied and the shape of slip ring may be such that rotation would be allowed between the slips and the mandrel—but for thechannels99. Each ofslips58 may be constructed of non-metallic composite materials, but each slip also includes a metallic insert62 disposed in outer surface63. Metallic inserts62 may each have a wicker design as shown in the figures to facilitate a locked engagement with acasing wall24. Metallic inserts62 may be molded intoslips58 such that slips58 and inserts62 comprise a single piece as shown in FIG. 1, however, as shown in the embodiment shown in FIGS. 11-13, metallic inserts62 may also be mechanically attached toslips58 by a fastener, for example screws65. Metallic inserts62 may be constructed of low density metallic materials such as cast iron, which may heat treated to facilitate hardening such that inserts62 can penetratecasing24, while maintaining small, brittle portions such that they do not hinder drilling operations. For example, metallic inserts62 may be hardened to approximately plus or minus fifty-five Rockwell C hardness. Metallic inserts62 may be integrally formed withslips58, for example, by injection molding the composite material that comprises slips58 around metallic insert62.

Adjacent slips58 is aring64.Ring64 is a solid non-metallic piece with an inner surface66 that may match the cross-section ofmandrel4, for example inner surface66 may be hexagonal. However, inner surface66 may be any non-circular surface that precludes rotation betweenring64 andmandrel4. For example, inner surface66 may be square, whilemandrel4 has an outer surface that is hexagonal or octagonal, but rotation between the two is still precludedRing64, like the other components mounted tomandrel4, may have substantially circular outer diameter. The match between inner surface66 and the cross-section ofmandrel4 advantageously precludes rotation betweenring64 andmandrel4.

Ring64 abuts asecond end cap68.Second end cap68 may be a non-metallic material that is easily drillable, for example injection molded phenolic or other similar material.Second end cap68 may be attached tomandrel4 by a plurality of non-metallic composite pins70, and/or attached via an adhesive. Composite pins70 are arranged in different planes to distribute any shear forces transmitted thereto.Second end cap68 prevents any of the other plug components (discussed above) from sliding offsecond end72 ofmandrel4. In the embodiment shown in the Figures,second end cap68 exhibits an internal surface matching the non-circular cross-section ofmandrel4 which creates a rotational lock between the end cap and mandrel, however, the internal surface of thesecond end cap68 may be any non-circular surface that precludes rotation between the end cap andmandrel4. For example, the internal surface ofsecond end cap68 may be square, whilemandrel4 has an outer surface that is hexagonal or octagonal, but rotation between the two is still precluded.Second end72 ofmandrel4 may include a locking mechanism, for example taperedsurface74, that rotationally locks plug assembly2 with another abutting plug assembly (not shown). Taperedsurface74 is engagable with taperedsurface14 ofend cap10 such that rotation between two plugs2 is precluded whensurfaces74 and14 are engaged.

Second end72 of plug2 includes twogrooves76 extending aroundmandrel4.Grooves76 are receptive of acollet78.Collet78 is part of anadapter kit80.Adapter kit80 includes abushing82 receptive of a setting tool500 (not shown in FIG. 1, but shown in FIGS.11-13).Bushing82 is receptive, for example of a Baker E-4 wireline pressure setting assembly (not shown), but other setting tools available from Owen and Schlumberger may be used as well. The setting tools include, but are not limited to: wireline pressure setting tools, mechanical setting tools, and hydraulic setting tools.Adjacent bushing82 is a settingsleeve84. Settingsleeve84 extends between the setting tool (not shown) and bridge plug2. Adistal end86 of settingsleeve84 abutsring64.Adapter kit80 exhibits a second connection point to the setting tool (not shown) at theproximal end88 of a setting mandrel90. Setting mandrel90 is part ofadapter kit80. Settingsleeve84 and setting mandrel90 facilitate the application of forces on plug2 in opposite directions. Forexample setting sleeve84 may transmit a downward force (to the right as shown in the Figures) on plug2 while setting mandrel90 transmits an upward force (to the left as shown in the Figures). The opposing forces enable compression of packingelement42 and anchoringassembly16. Rigidly attached to setting mandrel90 is asupport sleeve92.Support sleeve92 extends the length ofcollet78 between settingsleeve84 andcollet78.Support sleeve92locks collet78 in engagement withgrooves76 ofmandrel4.Collet78 may be shearably connected to setting mandrel90, for example byshear pins96 or other shearing device such as a shear ring (not shown).

It will be understood by one of skill in the art with the benefit of this disclosure that one or more of the non-metallic components may include plastics that are reinforced with a variety of materials. For example, each of the non-metallic components may comprise reinforcement materials including, but not limited to, glass fibers, metallic powders, wood fibers, silica, and flour. However, the non-metallic components may also be of a non-reinforced recipe, for example, virgin Peek, Ryton, or Teflon polymers. Further, in some embodiments, the non-metallic components may instead be metallic component to suit a particular application. In a metallic-component situation, the rotational lock between components and the mandrel remains as described above.

Operation and setting of plug2 is as follows. Plug2, attached to a setting tool viaadapter kit80, is lowered into a wellbore to the desired setting position as shown in FIGS. 1 and 13.Bushing82 and its associated settingsleeve84 are attached to a first portion of the setting tool (not shown) which supplies a downhole force. Setting mandrel90, with its associated components includingsupport sleeve92 andcollet78, remain substantially stationary as the downhole force is transmitted through settingsleeve84 to ring64. The downhole force load is transmitted via settingsleeve84 andring64 to shearpins56 ofsecond cone52. At a predetermined load, for example a load of approximately 1500 pounds, shear pins56 shear and packingelement42 begins its radial outward movement into sealing engagement withcasing wall24 as shown in FIG.5. As the setting force from settingsleeve84 increases and packingelement42 is compressed, second plurality ofslips58 traversessecond cone52 and eventuallysecond ring60 breaks and each of second plurality ofslips58 continue to traversesecond cone52 until metallic inserts62 of each penetrates casingwall24 as shown in FIGS. 6 and 12. Similar to the operation of anchoring slips58, the load transmitted by settingsleeve84 also causes shear pins38 betweenfirst cone26 andmandrel4 to shear at, for example, approximately 1500 pounds, and allow first plurality ofslips18 to traversefirst cone26. First plurality ofslips18 traversefirst cone26 and eventuallyfirst ring25 breaks and each of first plurality ofslips18 continue to traversefirst cone26 untilmetallic inserts22 of each penetrates casingwall24. Force supplied through settingsleeve84 continues and at, for example, approximately 3000 pounds of force, first and second pluralities ofslips18 and56 are set incasing wall24 as shown in FIGS. 6 and 12.

As the force transmitted by settingsleeve84 continues to increase, eventuallyfirst cone26 will break and metallic cone inserts28 collapse onmandrel4 as shown in FIGS. 7 and 12.First cone26 may break, for example, at approximately 4500 pounds. Asmetallic inserts28 collapse onmandrel4, the wickers bite intomandrel4 and lock the mandrel in place with respect to the outer components. Force may continue to increase via settingsleeve84 to further compress packingelement42 into a sure seal withcasing wall24.Packing element42 may be completely set at, for example approximately 25,000 pounds as shown in FIG.8. At this point, setting mandrel90 begins to try to move uphole via a force supplied by the setting tool (not shown), butmetallic inserts28 infirst cone26 prevent much movement. The uphole force is transmitted via setting mandrel90 to shearpins96, which may shear at, for example 30,000 pounds. Referring to FIGS. 9 and 11, as shear pins96 shear, setting mandrel90 andsupport sleeve92 move uphole. As setting mandrel90 andsupport sleeve92 move uphole,collet78 is no longer locked, as shown in FIGS. 10 and 11. Whencollet78 is exposed, any significant force will snapcollet78 out ofrecess76 inmandrel4 andadapter kit80 can be retrieved to surface via its attachment to the setting tool (not shown).

With anchoringassembly16, packingelement42, and first conemetallic insert28 all set, any pressure build up on either side of plug2 will increase the strength of the seal. Pressure from uphole may occur, for example, as a perforated zone is fractured.

In an alternative embodiment of the present invention shown in FIGS. 18-20,hole6 inmandrel4 may extend all the way through, with a valve such asvalves100,200, or300 shown in FIGS. 18-20, being placed in the hole. The through-hole and valve arrangement facilitates the flow of cement, gases, slurries, or other fluids throughmandrel4. In such an arrangement, plug assembly2 may be used as acement retainer3. In the embodiment shown in FIG. 18, a flapper-type valve100 is disposed inhole6.Flapper valve100 is designed to provide a back pressure valve that actuates independently of tubing movement and permits the running of a stinger ortailpipe102 below the retainer.Flapper valve100 may include aflapper seat104, aflapper ring106, a biasing member such asspring108, and aflapper seat retainer110.Spring108biases flapper ring106 in a closeposition covering hole6, however a tail pipe orstinger102 may be inserted intohole6 as shown in FIG.18. Whentailpipe102 is removed fromretainer3,spring108 forces flapperseat104 closed. In the embodiment shown in FIG. 19, a ball-type valve200 is disposed inhole6.Ball valve200 is designed to provide a back pressure valve as well, but it does not allow the passage of a tailpipe throughmandrel4.Ball valve200 may include aball204 and a biasing member such asspring206.Spring206biases ball204 to a closedposition covering hole6, however, astinger202 may be partially inserted into the hole as shown in FIG.19. Whenstinger202 is removed fromretainer3,spring206forces ball204 to closehole6. In the embodiment shown in FIG. 20, aslide valve300 is disposed inhole6.Slide valve300 is designed to hold pressure in both directions.Slide valve300 includes acollet sleeve302 facilitating an open and a closed position.Slide valve300 may be opened as shown in FIG. 20 by inserting astinger304 that-shifts collet sleeve302 to the open position. Asstinger304 is pulled out ofretainer3, the stinger shiftscollet sleeve302 back to a closed position. It will be understood by one of skill in the art with the benefit of this disclosure that other valve assemblies may be used to facilitatecement retainer3. The embodiments disclosed in FIGS. 18-20 are preferred exemplary assemblies, but other valving assemblies are also contemplated by the present invention.

Because plug2 includes all non-metallic components other thanmetallic inserts22,28, and62, plug assembly2 may be easily drilled out as desired with only a coiled tubing drill bit and motor. In addition, as described above, all components are rotationally locked with respect tomandrel4, further enabling quick drill-out.First end cap10 also rotationally locks with taperedsurface74 ofmandrel4 such that multiple plug drill outs are also advantageously facilitated by the described apparatus.

While the invention may be adaptable to various modifications and alternative forms, specific embodiments have been shown by way of example and described herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. Moreover, the different aspects of the disclosed methods and apparatus may be utilized in various combinations and/or independently. Thus the invention is not limited to only those combinations shown herein, but rather may include other combinations. For example, the disclosed invention is also applicable to any permanent or retrievable packer taking advantage of the non-circular surfaces so as to improve the millability of each, the invention is not limited to plugs.

Claims (68)

What is claimed is:

1. A subterranean apparatus comprising:

a mandrel having an outer surface and a non-circular cross-section; and

a packing element arranged about the mandrel, the packing element having a non-circular inner surface such that rotation between the mandrel and the packing element is precluded as the outer surface of the mandrel and inner surface of the packing element interfere with one another in rotation.

2. The apparatus ofclaim 1 wherein the outer surface of the mandrel and the inner surface of the packing element exhibit matching shapes.

3. The apparatus ofclaim 1 wherein the mandrel comprises non-metallic materials.

4. The apparatus ofclaim 3 wherein the non-metallic materials comprise reinforced plastics.

5. The apparatus ofclaim 1 wherein the non-circular cross-section is a hexagon.

6. The apparatus ofclaim 1 further comprising an anchoring assembly arranged about the mandrel, the anchoring assembly having a non-circular inner surface such that concentric rotation between the mandrel and the anchoring assembly is precluded.

7. The apparatus ofclaim 6 wherein the non-circular inner surface matches the mandrel outer surface.

8. The apparatus ofclaim 6 wherein the anchoring assembly further comprises a first plurality of slips arranged about the non-circular mandrel outer surface, the slips being configured in a non-circular loop such that rotation between the mandrel and the first plurality of slips is precluded by interference between the loop shape and the mandrel outer surface shape.

9. The apparatus ofclaim 8 wherein the slips are arranged in a shape matching the outer surface of the mandrel.

10. The apparatus ofclaim 8 wherein the first plurality of slips comprise non-metallic materials.

11. The apparatus ofclaim 8 further comprising a metallic insert integrally formed into or mechanically attached to each of the plurality of slips wherein the metallic insert is engagable with a wellbore wall.

12. The apparatus ofclaim 8 wherein the first plurality of slips abuts a first cone, the first cone facilitating radial outward movement of the slips into engagement with a wellbore wall upon traversal of the plurality of slips along the first cone.

13. The apparatus ofclaim 12 wherein the first cone is arranged about the mandrel, the first cone comprising a non-circular inner surface such that rotation between the mandrel and the first cone is precluded by interference between the first cone inner surface shape and the mandrel outer surface shape.

14. The apparatus ofclaim 13 wherein the non-circular inner surface of the first cone matches the outer non-circular surface of the mandrel.

15. The apparatus ofclaim 12 wherein the first cone further comprises a plurality of channels, each of the plurality of channels being receptive of at least one of the plurality of slips, the channels being arranged such that rotation between the first cone and the slips is precluded.

16. The apparatus ofclaim 12 wherein the first cone comprises non-metallic materials.

17. The apparatus ofclaim 12 further comprising at least one shearing device disposed between the first cone and the mandrel, the at least one shearing device adapted to shear upon the application of a predetermined force.

18. The apparatus ofclaim 8 further comprising a second plurality of slips arranged about the non-circular mandrel outer surface, the slips being configured in a non-circular loop such that concentric rotation between the mandrel and the second plurality of slips is precluded by interference between the loop shape and the mandrel outer surface shape.

19. The apparatus ofclaim 18 wherein the slips are arranged in a shape matching the outer surface of the mandrel.

20. The apparatus ofclaim 18 wherein the second plurality of slips comprise non-metallic materials.

21. The apparatus ofclaim 18 further comprising a metallic insert integrally formed into or mechanically attached to each of the second plurality of slips, wherein the metallic insert is engagable with a wellbore wall.

22. The apparatus ofclaim 18 further comprising a second collapsable cone arranged about the non-circular outer surface of the mandrel, the second collapsable cone comprising a non-cylindrical inner surface such that rotation between the mandrel and second collapsable cone is precluded, wherein a second plurality of slips abuts the second collapsable cone, facilitating radial outward movement of the slips into engagement with the wellbore wall upon traversal of the second plurality of slips along the second collapsable cone.

23. The apparatus ofclaim 22 wherein the non-cylindrical inner surface of the second collapsable cone matches the outer non-circular surface of the mandrel.

24. The apparatus ofclaim 22 wherein the second collapsable cone comprises non-metallic materials.

25. The apparatus ofclaim 24 wherein the second collapsable cone is adapted to collapse upon the application of a predetermined force.

26. The apparatus ofclaim 22 wherein the second collapsable cone further comprises at least one metallic insert attached thereto, the at least one metallic insert facilitating a locking engagement between the cone and the mandrel.

27. The apparatus ofclaim 22 wherein the locking engagement precludes rotation and translation between the anchoring assembly and the mandrel.

28. The apparatus ofclaim 22 further comprising at least one shearing device disposed between the second collapsable cone and the mandrel, the at least one shearing device being adapted to shear upon the application of a predetermined force.

29. The apparatus ofclaim 18 wherein the packing element is disposed between the first cone and the second collapsable cone.

30. The apparatus ofclaim 1 further comprising a first cap attached to a first end of the mandrel.

31. The apparatus ofclaim 30 wherein the first cap comprises non-metallic materials.

32. The apparatus ofclaim 30 wherein the first cap is attached to the mandrel by a plurality of non-metallic pins.

33. The apparatus ofclaim 30 wherein the first cap abuts a first plurality of slips.

34. The apparatus ofclaim 1 wherein the packing element further comprises a first end element, a second end element, and an elastomer disposed therebetween.

35. The apparatus ofclaim 34 wherein the elastomer is adapted to form a seal about the non-circular outer surface of the mandrel upon compressive force applied by the first and second end elements.

36. The apparatus ofclaim 30 further comprising a second cap attached to a second end of the mandrel.

37. The apparatus ofclaim 36 wherein the second cap comprises non-metallic materials.

38. The apparatus ofclaim 36 wherein the second cap is attached to the mandrel by a plurality of non-metallic pins and exhibits a non-circular inner surface such that rotation between the mandrel and the second cap is precluded as the outer surface of the mandrel and inner surface of the second cap interfere with one another in rotation.

39. The apparatus ofclaim 38 wherein the inner surface of the second cap matches the non-circular outer surface of the mandrel.

40. The apparatus ofclaim 36 wherein the second cap abuts a second plurality of slips.

41. The apparatus ofclaim 36 wherein the first cap is adapted to rotationally lock with a top surface of the mandrel of a second identical plug.

42. The apparatus ofclaim 41 wherein the first cap and the top surface of the mandrel are each tapered to facilitate the rotational lock therebetween.

43. The apparatus ofclaim 1 further comprising a hole in the mandrel extending at least partially therethrough.

44. The apparatus ofclaim 43 wherein the hole extends all the way through the mandrel.

45. The apparatus ofclaim 44 further comprising a valve arranged in the hole facilitating the flow of cement, fluids, gases, or slurries through the mandrel.

46. A subterranean device comprising:

a mandrel;

a first cone arranged about an outer diameter of the mandrel;

a first plurality of slips arranged about the first cone;

a second cone spaced from the first cone and arranged about the outer diameter of the mandrel;

a second plurality of slips arranged about the second cone;

a metallic insert disposed in an inner surface of the second cone and adjacent to the mandrel;

a packing element disposed between the first and second cones;

wherein the first and second pluralities of slips are lockingly engagable with the wall of a wellbore and the metallic insert is lockingly engagable with the mandrel.

47. The device ofclaim 46 wherein the first and second pluralities of slips are rotationally locked within channels formed in the first and second cones.

48. The device ofclaim 46 wherein the second cone is collapsable onto the mandrel upon the application of a predetermined force.

49. The device ofclaim 46 wherein the mandrel, cones, and slips comprise non-metallic materials.

50. The device ofclaim 46 wherein a cross-section of the mandrel is non-circular.

51. The device ofclaim 46 wherein each of first and second cones comprise non-circular inner surfaces such that rotation between the mandrel and the cones is precluded.

52. A slip assembly for use on subterranean apparatus comprising:

a first cone with at least one channel therein;

a first plurality of slips, each having an attached metallic insert, the first slips being arranged about the first cone in the at least one channel of the first cone;

a second collapsable cone having at least one channel, an interior surface, and an attached metallic insert disposed in the interior surface;

a second plurality of slips, each having an attached metallic insert, the second slips being arranged about the second cone in at least one channel of the second collapsable cone;

wherein the second collapsable cone is adapted to collapse upon the application of a predetermined force.

53. The assembly ofclaim 52 wherein each of first and second cones and first and second pluralities of slips comprise non-metallic materials.

54. The assembly ofclaim 52 wherein the first and second pluralities of slips are adapted to traverse first and second cones until the slips lockingly engage with a wellbore wall.

55. The assembly ofclaim 52 wherein the metallic insert of the second collapsable cone is adapted to lockingly engage with a mandrel upon the collapse of the cone.

56. The assembly ofclaim 52 wherein the first and second cones each have a non-circular inner surface such that the shape of the non-circular inner surfaces precludes rotation around a non-circular mandrel.

57. The assembly ofclaim 56 wherein the non-circular inner surfaces of the first and second cones match the non-circular outer surface of the mandrel.

58. A method of isolating a portion of a well comprising the steps of:

running a plug into a well, the plug comprising a mandrel with a non-cylindrical outer surface, an anchoring assembly, and a packing element arranged about the mandrel;

setting the packing element by the application of force;

locking the plug in place within the well; and

locking the anchoring assembly to the mandrel.

59. The method ofclaim 58 wherein the anchoring assembly further comprises

a first cone arranged about the outer surface of the mandrel;

a first plurality of slips arranged about the first cone;

a second cone spaced from the first cone and arranged about the outer diameter of the mandrel;

a second plurality of slips arranged about the second cone;

a metallic insert disposed in an inner surface of the second cone and adjacent to the mandrel;

wherein the first and second pluralities of slips are lockingly engagable with the wall of a wellbore and the metallic insert is lockingly engagable with the mandrel.

60. The method ofclaim 59 wherein the first and second cones each include a plurality of channels receptive of the first and second pluralities of slips.

61. The method ofclaim 58 wherein the step of running the plug into the well comprises running the plug on wireline.

62. The method ofclaim 58 wherein the step of running the plug into the well comprises running the plug on a mechanical or hydraulic setting tool.

63. The method ofclaim 59 wherein the step of locking the plug within the well further comprises the first and second pluralities of slips traversing the first and second cones and engaging with a wall of the, well.

64. The method ofclaim 59 wherein the step of locking the anchoring assembly to the mandrel further comprises collapsing the second cone and engaging the second cone metallic insert with the mandrel.

65. A method of drilling out a subterranean apparatus comprising the steps of:

running a drill into a wellbore; and

drilling the apparatus;

wherein the apparatus is substantially non-metallic and comprises

a mandrel having a non-cylindrical outer surface; and

a packing element arranged about the mandrel, the packing element having a non-cylindrical inner surface precluding rotation between the packing element and the mandrel.

66. The method ofclaim 65 wherein the non cylindrical inner surface of the packing element matches the mandrel outer surface.

67. The method ofclaim 65 wherein the step of running the drill into the wellbore is accomplished by using a coiled tubing.

68. The method ofclaim 67 wherein the step of drilling is accomplished by a coiled tubing motor and bit.

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